Microstructure and Mechanical Properties of Al-Li Alloys with Different Li Contents Prepared by Selective Laser Melting.

Research on the development of new lightweight Al-Li alloys using a selective laser melting process has great potential for industrial applications. This paper reports on the development of novel aluminum-lithium alloys using selective laser melting technology. Al-Cu-Li-Mg-Ag-Sc-Zr pre-alloyed powders with lithium contents of 1 wt.%, 2 wt.% and 3 wt.%, respectively, were prepared by inert gas atomization. After SLM process optimization, the microstructure and mechanical properties of the as-printed specimens were investigated. The densifications of the three newly developed alloys were 99.51%, 98.96% and 92.01%, respectively. They all had good formability, with the lithium loss rate at about 15%. The as-printed alloy with 1% Li content presented good comprehensive properties, with a yield strength of 413 ± 16 MPa, an ultimate tensile strength of 461 ± 12 MPa, and an elongation of 14 ± 1%. The three alloys exhibited a layered molten pool stacking morphology and had a typical heterostructure. The columnar crystals and equiaxed fine grains were alternately arranged, and most of the precipitated phases were enriched at the grain boundaries. The change in Li content mainly affected the precipitation of the Cu-containing phase. When the Li content was 1 wt.%, the following occured: θ phase, T1 phase and TB phase. When Li increased to 2 wt.%, T1 and T2 phases precipitated together. When Li reaches 3 wt.%, δ' phase precipitated with T2 phase. This study provides useful guidance for the future SLM forming of new crack-free and high-strength Al-Li alloys.

Acoustic emission characteristics of micro-discharges in initial pulsed PEO process on 60% SiCp/Al composite.

The initial discharge process of pulsed plasma electrolytic oxidation (PEO) on the 60% SiCp/2009 aluminum metal matrix composite (Al MMC) in silicate solution was monitored by acoustic emission (AE) technique. Parameters and correlations of AE signals on the Al MMC sample and under water were analyzed, and their generation mechanism was discussed. It was found that the peak amplitudes of AE signals and AE hits during the pulse time quickly increased with the increase of micro-discharge intensity, and the absolute energy of AE signals improved several orders of magnitude. Moreover, different from the peak amplitude, duration and rise time, the duration and count had a strong correlation. Elastic stress waves resulted from the microjet of plasma bubble collapse, the inner-surface friction inside discharge channel, the expansion-shrinkage process of plasma bubbles and micro-crack propagation during rapid solidification of melt are sources of AE signals on the Al MMC sample during the pulse time. However, the expansion-shrinkage process of plasma bubbles plays a key role in the generation of underwater AE signals. In the pause time of one pulse period, the bursting and moving of vapor bubbles result in weak AE signals. It is demonstrated that the AE technique can effectively characterize the features of micro-discharges within a pulse period.

Measuring the Capability of Biological Incident Rescue Teams in China: A Fuzzy Analytic Hierarchy Process Based Model - Tianjin Municipality, China, 2022-2023.

Introduction: The swift advancement of biotechnology has presented both opportunities and challenges to our society, thrusting biosafety to the forefront of concern. Consequently, the evaluation of rescue capabilities in the event of a bioterrorism incident becomes of paramount importance. Currently, there is a notable absence of specific measurement criteria and a comprehensive evaluation system. This paper aims to establish a systematic approach towards assessing emergency response capabilities in the context of bioterrorism incidents. Methods: We employed an enhanced Delphi methodology to establish an index evaluation framework. Subsequently, the weight of the judgment matrix was ascertained via the application of the fuzzy comprehensive evaluation approach. This led to the creation of a fuzzy comprehensive evaluation model for bioterrorism rescue capability. Results: A modified Delphi study was conducted involving 11 experts across two rounds, achieving a response rate of 100%. The Kendall coordination coefficients recorded in the first and second rounds were 0.303 and 0.632, respectively (P<0.05). Upon comprehensive analysis involving score, coefficient of variation, and full score ratio, we distinguished five primary indicators and 25 secondary indicators. Subsequently, an evaluation model was developed based on the Analytic Hierarchy Process (AHP) tailored to assess the response to a rescue from bioterrorism. Discussion: The expert panel confirmed consensus on all aspects of the model, validating its comprehensive content. The succeeding course of action involves converting the assessment model to a measurable scale, affirming its functionality, and implementing it in practical evaluation tasks to further enhance the capabilities of the biological incident rescue team.

Knowledge, attitudes, and practices associated with bioterrorism preparedness in healthcare workers: a systematic review.

Introduction: Bioterrorism is an important issue in the field of biosecurity, and effectively dealing with bioterrorism has become an urgent task worldwide. Healthcare workers are considered bioterrorism first responders, who shoulder essential responsibilities and must be equipped to deal with bioterrorism. This study aims to extract and summarize the main research components of the bioterrorism knowledge, attitude, and practice dimensions among healthcare workers. Method: This study utilized a systematic review research design based on the PRISMA 2020 guidelines. A literature search was conducted in the PubMed, Web of Science, and Scopus databases for peer-reviewed literature, and the Mixed Methods Appraisal Tool (MMAT) version 2018 was used to assess the quality of the literature. Result: A total of 16 studies were included in the final selection. Through the analysis and summary of the included studies, three main aspects and 14 subaspects of the knowledge dimension, three main aspects and 10 subaspects of the attitude dimension, and two main aspects and six subaspects of the practice dimension were extracted. Conclusion: This study conducted a literature review on bioterrorism knowledge, attitudes, and practices for healthcare workers based on the PRISMA 2020 guidelines. The findings can guide improvements in health literacy and provide beneficial information to professional organizations that need to respond effectively to bioterrorism.

In situ monitoring of initial plasma electrolytic oxidation process on 60 vol. % SiCp/2009 aluminum matrix composite by sound and vibration measurement techniques.

The initial discharge process of plasma electrolytic oxidation (PEO) on the 60 vol. % SiCP/2009 aluminum matrix composite in silicate solution was in situ monitored by sound and vibration measurement techniques. The underwater sound, airborne sound, and sample vibration signals were detected in the initial 120 s of the PEO process, and their generation mechanism was discussed. In terms of waveforms and spectrograms of the sound and vibration signals, the initial PEO process can be divided into five stages: conventional anodizing stage (I), glow discharge stage (Ⅱ), tiny spark discharge stage (Ⅲ), large spark discharge stage (Ⅳ), and strong spark discharge stage (Ⅴ). The sound and vibration signals during the PEO process are attributed to the evolution of bubbles, which are from the plasma discharge, electrochemical reactions, and vaporization of electrolyte under Joule heat. In stage I, these signals completely come from the bubbles produced by the evaporative electrolyte and electrochemical reactions. In stages Ⅱ-Ⅴ, the bubbles from the plasma discharge gradually become the main source of these signals with increasing discharge intensity. In addition, the spike peaks on the waveforms of these signals at stage Ⅴ are related to the strong discharge sparks. These results demonstrate that sound and vibration measurement techniques can effectively monitor the PEO discharge process.

Research on In-Plane Deformation Performance of Rotating Honeycomb Structures.

Most natural materials have rotational and hierarchical properties, so they can show excellent mechanical properties such as shear resistance and impact resistance. In order to further improve the energy absorption characteristics of vibration absorbing structures, a new type of honeycomb structure with integral rotation and group rotation is designed and characterized. The effects of the geometrical parameters of rotation Angle on the impact deformation mode, stress response curve and energy absorption characteristics of the honeycomb structure are studied through numerical simulation and experimental design. The results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is the results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is increased by 6%, the bearing capacity is increased by 320 N, and the crushing force efficiency is increased by 2%. Compared with the whole cell and the group cell, the specific absorption energy increased by 35%, 73% and 71%. The results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the optimization of crashworthiness structural design.

Association Between Exposure to Ozone (O3) and the Short-Term Effect on Tuberculosis Outpatient Visits: A Time-Series Study in 16 Cities of Anhui Province, China.

Introduction: Evidence has shown that air pollutant exposure plays a vital role in the progression of tuberculosis (TB). The aim of this research was to assess the short-term effects of ozone (O3) exposure and TB outpatient visits in 16 prefecture-level cities of Anhui, China, 2015-2020. Methods: Distributed lag nonlinear model (DLNM), Poisson generalized linear regression model and random effects model were applied in this study. The effects of different age and gender on TB were investigated by stratified analysis, and then we performed sensitivity analyses to verify the stability of the results. Results: A total of 186,623 active TB cases were registered from January 1, 2015 to December 31,2020 in Anhui. The average concentration of ozone is 92.77 ± 42.95 µg/m3. The maximum lag-specific and cumulative relative risk (RR) of TB outpatient visits was 1.0240 (95% CI: 1.0170-1.0310, lag 28 days) for each 10 µg/m³ increase in O3 in the single-pollutant model. Estimation for 16 prefecture-level cities indicated that the strong association between O3 and the risk of TB outpatient visits was in tongling (RR = 1.0555, 95% CI: 1.0089-1.1042), Suzhou (RR = 1.0475, 95% CI: 1.0268-1.0687), wuhu (RR = 1.0358, 95% CI: 1.0023-1.0704). Stratified analysis showed that the health effects of ozone exposure remained significant in male and older adults, and there was no significant association between exposure to ozone in children and adolescents and the risk of tuberculosis. Discussion: We found that ozone exposure increases the risk of TB infection in outpatient patients, with males and the elderly being more susceptible, and it is necessary for government departments to develop targeted publicity and prevention measures in response to the local air quality conditions.

Successful Large Hospital Evacuation With 11 350 Patients Transferred in the 2021 Zhengzhou Flood.

OBJECTIVES: This is a case report of a huge hospital evacuation with 11 350 inpatients in the 2021 Zhengzhou flood in China, using a mixed methods analysis. METHODS: The qualitative part was a content analysis of semi-structured interviews of 6 key hospital staff involved in evacuation management. The evacuation experience was reviewed according to the 4 stages of disaster management: prevention, preparation, response, and recovery. RESULTS: Because of unprecedented torrential rain, the flood exceeded expectations, and there was a lack of local preventive measures. In preparation, according to the alert, the evacuation was planned to reduce the workload on inpatients and to accept the surge of medical needs by the flood. In response, the prioritization of critically ill patients and large-scale collaboration of hospital staff, rescue teams, and accepting branch made it possible to successfully transfer all 11 350 inpatients. In recovery, restoring medical services and a series of activities to improve the hospital's vulnerability were carried out. CONCLUSIONS: A hospital evacuation is one of the strategies of the business continuity plan of a hospital. For the evacuation, leadership and collaboration were important. Challenges such as prolonged roadway flooding and the infrastructure issues were needed to be addressed throughout the evacuation process.

Composition Design and Tensile Properties of Additive Manufactured Low Density Hf-Nb-Ta-Ti-Zr High Entropy Alloys Based on Atomic Simulations.

High-entropy alloy (HEA) is a new type of multi-principal alloy material and the Hf-Nb-Ta-Ti-Zr HEAs have attracted more and more attention from researchers due to their high melting point, special plasticity, and excellent corrosion resistance. In this paper, in order to reduce the density of the alloy and maintain the strength of the Hf-Nb-Ta-Ti-Zr HEAs, the effects of high-density elements Hf and Ta on the properties of HEAs were explored for the first time based on molecular dynamics simulations. A low-density and high-strength Hf0.25NbTa0.25TiZr HEA suitable for laser melting deposition was designed and formed. Studies have shown that the decrease in the proportion of Ta element reduces the strength of HEA, while the decrease in Hf element increases the strength of HEA. The simultaneous decrease in the ratio of Hf and Ta elements reduces the elastic modulus and strength of HEA and leads to the coarsening of the alloy microstructure. The application of laser melting deposition (LMD) technology refines the grains and effectively solves the coarsening problem. Compared with the as-cast state, the as-deposited Hf0.25NbTa0.25TiZr HEA obtained by LMD forming has obvious grain refinement (from 300 µm to 20-80 µm). At the same time, compared with the as-cast Hf0.25NbTa0.25TiZr HEA (σs = 730 ± 23 MPa), the as-deposited Hf0.25NbTa0.25TiZr HEA has higher strength (σs = 925 ± 9 MPa), which is similar to the as-cast equiatomic ratio HfNbTaTiZr HEA (σs = 970 ± 15 MPa).

Identification of ZmBK2 Gene Variation Involved in Regulating Maize Brittleness.

Maize stalk strength is a crucial agronomic trait that affects lodging resistance. We used map-based cloning and allelic tests to identify a maize mutant associated with decreased stalk strength and confirmed that the mutated gene, ZmBK2, is a homolog of Arabidopsis AtCOBL4, which encodes a COBRA-like glycosylphosphatidylinositol (GPI)-anchored protein. The bk2 mutant exhibited lower cellulose content and whole-plant brittleness. Microscopic observations showed that sclerenchymatous cells were reduced in number and had thinner cell walls, suggesting that ZmBK2 affects the development of cell walls. Transcriptome sequencing of differentially expressed genes in the leaves and stalks revealed substantial changes in the genes associated with cell wall development. We constructed a cell wall regulatory network using these differentially expressed genes, which revealed that abnormal cellulose synthesis may be a reason for brittleness. These results reinforce our understanding of cell wall development and provide a foundation for studying the mechanisms underlying maize lodging resistance.

A synthetic Tn-BSA conjugate vaccine bearing chitotriose as built-in adjuvant.

Chitotriose (CTS), the hydrolysate of chitosan, is readily soluble in water because of the shorter chain lengths of the oligomers and the free amino groups in the d-glucosamine units. In the current study, we report the synthesis of novel conjugate vaccine Tn-BSA-CTS with chitotriose as built-in adjuvant, along with an evaluation of the effect of adjuvant chitotriose (CTS). Immunological evaluations of the resultant conjugate vaccine revealed that Tn-BSA-CTS could provoke the highest titers of IgG antibodies (102,400). The Tn-BSA-CTS conjugate remarkably enhanced both humoral and cellular immunity. The obtained results demonstrate the potential of CTS as a novel vaccine adjuvant in the development of antitumor vaccine and the covalent linkage of tumor vaccine to CTS might be available strategy to increase the efficacy against cancer.

Microstructure, Mechanical Properties and Fracture Behavior of Micron-Sized TiB2/AlZnMgCu(Sc,Zr) Composites Fabricated by Selective Laser Melting.

In this paper, micron-sized TiB2/AlZnMgCu(Sc,Zr) composites were fabricated by selective laser melting (SLM) using directly mixed powder. Nearly fully dense (over 99.5%) and crack-free SLM-fabricated TiB2/AlZnMgCu(Sc,Zr) composite samples were obtained and its microstructure and mechanical properties were investigated. It is found that the laser absorption rate of powder is improved by introducing micron-sizedTiB2 particles, then the energy density required for SLM forming can be reduced, and the densification can finally be improved. Some crystalline TiB2 formed a coherent relationship with the matrix, while some broken TiB2 particles did not, however, MgZn2 and Al3(Sc,Zr) can perform as intermediate phases to connect these non-coherent surfaces to aluminum matrix. All these factors lead to an increase in strength of the composite. The SLM-fabricated micron-sized TiB2/AlZnMgCu(Sc,Zr) composite finally shows a very high ultimate tensile strength of ~646 MPa and yield strength of ~623 MPa, which are higher than many other aluminum composites fabricated by SLM, while maintaining a relatively good ductility of ~4.5%. The fracture of TiB2/AlZnMgCu(Sc,Zr) composite is occurred along the TiB2 particles and the bottom of the molten pool. This is due to the concentration of stress from the sharp tip of TiB2 particles and the coarse precipitated phase at the bottom of the molten pool. The results show that TiB2 plays a positive role in AlZnMgCu alloys fabricated by SLM, but finer TiB2 particles should be studied.

Triage Algorithms for Mass-Casualty Bioterrorism: A Systematic Review.

OBJECTIVES: To understand existing triage algorithms, propose improvement measures through comparison to better deal with mass-casualty incidents caused by bioterrorism. STUDY DESIGN: Systematic review. METHODS: Medline, Scopus and Web of Science were searched up to January 2022. The studies investigating triage algorithms for mass-casualty bioterrorism. Quality assessment was performed using the International Narrative Systematic Assessment tool. Data extractions were performed by four reviewers. RESULTS: Of the 475 titles identified in the search, 10 studies were included. There were four studies on triage algorithms for most bioterrorism events, four studies on triage algorithms for anthrax and two studies on triage algorithms for mental or psychosocial problems caused by bioterrorism events. We introduced and compared 10 triage algorithms used for different bioterrorism situations. CONCLUSION: For triage algorithms for most bioterrorism events, it is necessary to determine the time and place of the attack as soon as possible, control the number of exposed and potentially exposed people, prevent infection and determine the type of biological agents used. Research on the effects of decontamination on bioterrorism attacks needs to continue. For anthrax triage, future research should improve the distinction between inhalational anthrax symptoms and common disease symptoms and improve the efficiency of triage measures. More attention should be paid to triage algorithms for mental or psychosocial problems caused by bioterrorism events.

An automated method for the assessment of the rice grain germination rate.

The germination rate of rice grain is recognized as one of the most significant indicators of seed quality assessment. Currently, grain germination rate is generally determined manually by experienced researchers, which is time-consuming and labor-intensive. In this paper, a new method is proposed for counting the number of grains and germinated grains. In the coarse segmentation process, the k-means clustering algorithm is applied to obtain rough grain-connected regions. We further refine the segmentation results obtained by the k-means algorithm using a one-dimensional Gaussian filter and a fifth-degree polynomial. Next, the optimal single grain area is determined based on the area distribution curve. Accordingly, the number of grains contained in the connected region is equal to the area of the connected region divided by the optimal single grain area. Finally, a novel algorithm is proposed for counting germinated grains. This algorithm is based on the idea that the length of the intersection between the germ and the grain is less than the circumference of the germ. The experimental results show that the mean absolute error of the proposed method for germination rate is 2.7%. And the performance of the proposed method is robust to changes in grain number, grain varieties, scale, illumination, and rotation.

COVID-19 prevention and control measures and experiences during the 14th National Games of China: a qualitative interview study.

Background: The 14th National Games was the first sporting mass gathering to be held in China in the context of the COVID-19 pandemic. It may increase the risk of severe acute respiratory syndrome coronavirus 2 transmission. In order to reduce the spread of the virus during the 14th National Games, the Chinese government took a series of public health measures, and ultimately no confirmed cases were found in the 14th National Games venues. Objective: This study aimed to discuss preventive and control measures used to respond to the COVID-19 pandemic during the 14th National Games. Methods: Five experts were selected for this study using a snowball sampling method, and semistructured and in-depth interviews were conducted. Based on grounded theory, the transcriptions were analysed and coded using Nvivo 12 software. Results: A theoretical model of the COVID-19 prevention and control measures at the 14th National Games of China was constructed. The model contains seven main components: the health risks of mass gatherings, crowd management, emergency medical care, allocation of emergency medical resources, pandemic emergency drills, the pandemic prevention and control management platform (Quanyuntong app), and emergency response plans. Conclusion: The study showed that the deployment of emergency medical resources was the most important for mass gatherings. This study not only expanded the applications of grounded theory but also serves as a reference for future scholars when conducting more in-depth empirical studies on public health countermeasures for mass gatherings and can inform organizers when holding mass gatherings.

The PRISMA 2020 Statement: A System Review of Hospital Preparedness for Bioterrorism Events.

Hospitals are an important part of a nation's response to bioterrorism events. At present, research in this field is still in the initial stage. The number of related studies is small, the research direction is relatively concentrated, and a comprehensive analysis and standard evaluation system are lacking. This literature survey was conducted using PRISMA methodology. Collective information was gathered from PubMed, Web of Science, Scopus, and available grey literature sourced through Google and relevant websites. The studies were screened according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flowchart. Analysis and summary of the extracted data was performed according to the World Health Organization (WHO) Rapid Hospital Readiness Checklist (2020). Twenty-three articles were selected for review, data extraction, and data analysis. Referring to the WHO rapid hospital readiness checklist, six main indicator categories were determined, including emergency management, medical service capacity, surge capacity, laboratories, regional coordination, and logistical support, and fifty-two subcategories were finally identified. The study summarizes and analyzes the relevant literature on hospital disaster preparedness and extracts relevant capability elements, providing a reference for the preparation of hospitals against bioterrorism events and a basis for the design and development of hospital preparedness assessment indicators.

Stress exposure status and associated factors among Chinese People's Armed Police personnel: A cross-sectional study.

Background: MG (Mass gathering) deployment is one of the primary duties of Chinese People's Armed Police (PAP) personnel. Due to prolonged and repeated deployments in difficult conditions and harsh climates, military personnel are exposed to multiple stressors. Objectives: This study aims to understand the stress exposure status of armed police personnel during MG deployment and to explore its influencing factors. Methods: A cross-sectional study was conducted among PAP in 2021. We used a cluster random sampling to select 960 PAP personnel. Binary logistic regression was used to examine whether the stress exposure status was associated with factors such as demographics, health service utilization, and MG deployment. Results: Among 960 PAP personnel,83% of PAP personnel participated in MG in the past month, and 23.1% of PAP personnel suffered stress. The chi-square test showed that there were significant differences in MG'cycle time (p < 0.05). The binary logistic regression results showed that satisfaction with medical skills (p = 0.008), satisfaction with health environment (p = 0.031), satisfaction with medicine (OR = 0.640, 95%CI:0.436,0.938), and seeking health services (OR = 5.36, 95%CI:2.316,12.402) were associated with stress exposure status. However, age, and length of military service did not have any association with the stress exposure status of PAP personnel in this study. Conclusion: This study demonstrated that stress exposure status among PAP personnel was associated with MG deployment, and health service utilization. These findings can help policy-makers and clinicians to relieve the stress of the armed police personnel, as well as provide a basis for developing military health service security plans.

Application of the ARIMA Model in Forecasting the Incidence of Tuberculosis in Anhui During COVID-19 Pandemic from 2021 to 2022.

Objective: Forecasting the seasonality and trend of pulmonary tuberculosis is important for the rational allocation of health resources. In this study, we predict the incidence of pulmonary tuberculosis by establishing the autoregressive integrated moving average (ARIMA) model and providing support for pulmonary tuberculosis prevention and control during COVID-19 pandemic. Methods: Registered tuberculosis(TB) cases from January 2013 to December 2020 in Anhui province were analysed using traditional descriptive epidemiological methods. Then we used the monthly incidence rate of TB from January 2013 through June 2020 to construct ARIMA model, and used the incidence rate from July 2020 to December 2020 to evaluate the forecasting accuracy. Ljung Box test, Akaike's information criterion(AICc), Bayesian information criterion(BIC) and Realtive error were used to evaluate the model fitting and forecasting effect, Finally, the optimal model was used to forecast the expected monthly incidence of tuberculosis for 2021 and 2022 to learn about the incidence trend. Results: A total of 255,656 TB cases were registered. The reported rate of tuberculosis was highest in 2013 and lowest in 2020. The peak incidence was in March, Tongling (71.97/100,000), Chizhou (59.93/100,000), and Huainan (58.36/100,000) had the highest number of cases. The ratio of male to female incidence was 2.59:1, with the largest proportion of people being between 66 and 75 years old. The main occupation of patients was farmer. ARIMA (0, 1, 1) (0, 1, 1)12 model was the optimal model to forecast the incidence trend of TB. Conclusion: Tongling, Chizhou, and Huainan should strengthen measures for TB. In particular, the government should pay more attention on elderly people to prevent tuberculosis infections. The rate of TB patient registration and reporting has decreased under the pandemic of COVID-19. The ARIMA model can be a useful tool for predicting future TB cases.

Research on Microstructure and Properties of AlSi10Mg Fabricated by Selective Laser Melting.

In order to obtain high-performance aluminum alloy parts fabricated by selective laser melting, this paper investigates the relationship between the process parameters and microstructure properties of AlSi10Mg. The appropriate process parameters are obtained: the layer thickness is 0.03 mm, the laser power is 370 W, the scanning speed is 1454 mm/s, and the hatch spacing is 0.16 mm. With these process parameters, the ultimate tensile strength of the as-printed status is 500.7 ± 0.8 MPa, the yield strength is 311.5 ± 5.9 MPa, the elongation is 7.7 ± 0.5%, and the relative density is 99.94%. After annealing treatment at 275 °C for 2 h, the ultimate tensile strength is 310.8 ± 1.3 MPa, the yield strength is 198.0 ± 2.0 MPa, and the elongation is 13.7 ± 0.6%. The mechanical properties are mainly due to the high relative density, supersaturate solid solution, and fine dispersed Si. The supersaturate solid solution and nano-sized Si formed by the high cooling rate of SLM. After annealing treatment, the Si have been granulated and grown significantly. The ultimate tensile strength and yield strength are reduced, and the elongation is significantly improved.

A Maize Necrotic Leaf Mutant Caused by Defect of Coproporphyrinogen III Oxidase in the Porphyrin Pathway.

Lesion mimic mutants provide ideal genetic materials for elucidating the molecular mechanism of cell death and disease resistance. The maize necrotic leaf mutant (nec-t) is a recessive mutant with necrotic spots and yellow-green leaves. In this study, we found that nec-t was a light and temperature-dependent mutant. Map-based cloning and the allelic test revealed that nec-t was a novel allelic mutant of the Necrotic4 gene. Necrotic4 encodes the coproporphyrinogen III oxidase (CPX1), a key enzyme in the tetrapyrrole pathway, catalyzing coproporphyrinogen III oxidate to protoporphyrinogen IX. Subcellular localization showed that the necrotic4 protein was localized in the chloroplast. Furthermore, RNA-seq analysis showed that the Necrotic4 mutation caused the enhanced chlorophyll degradation and reactive oxygen species (ROS) response. The mechanism of plant lesion formation induced by light and temperature is not clear. Our research provides a basis for understanding the molecular mechanism of necrosis initiation in maize.